77MnA wire rod to trial produce high strength hot-dip galvanized steel strand

The steel wire strength requirement of hot-dip galvanized steel strand for electricity and telecommunication is high.The high strength galvanized steel strand was trial produced by adopting 77MnA steel wire rod and after the following procedure such as raw material production,surface treatment,drawing,degreasing,heat treatment,assistant plating,hot-dip galvanized and stranding etc.Normal temperature hydrochloric acid pickling,medium temperature phosphating process was adopted in surface treatment.Small pass compressibility was adopted in drawing process.The temperature of heat treatment was at 715 ℃~730 ℃.Heating time was about 124 s.The speed of take-up was 8.5 m/min.The galvanized temperature was at 455 ℃ ~ 465 ℃,galvanized time was 12 s at hot-dip galvanized.The thickness of zinc layer was controlled according to standard.When it was stranding,the payoff tension of 7 steel wires should be uniform.Practice shows that the technical index of steel wire for high strength galvanized steel strand produced by adopting trial production process reaches the requirements of GB/T 3428—2002.